package com.itheima.api_date.regex;

/**
 * @author Anomaly
 * @date 2022/12/30 15:18
 */
public class RegexDemo {
    public static void main(String[] args) {
        System.out.println(check("12345"));
        System.out.println(check("123456"));
        System.out.println(check("123456a"));
        System.out.println(check("123456789012345678901233"));
        System.out.println(check(null));
    }

    public static boolean check(String qq) {
        return qq != null && qq.matches("\\d{6,20}");
    }
}
